The following abbreviations are defined as follows:                DCH Dedicated Channel        DPDCH Dedicated Physical Data Channel        DPCCH Dedicated Physical Control Channel        E-DCH Enhanced Uplink DCH        E-DPDCH Enhanced DPDCH        E-DPCCH Enhanced DPCCH        E-TFC E-DCH Transport Format Combination        HSUPA High Speed Uplink Packet Access        IE Information Element        MAC Medium Access Control        Node B base station        PDU Protocol Data Unit        RLC Radio Link Control        RNC Radio Network Controller        RRC Radio Resource Control        SDU Service Data Unit        SG Serving Grant        TTI Transmission Timing Interval        UE User Equipment, e.g., a mobile terminal        
Of interest herein is the uplink DCH (EDCH) for packet data traffic in, for example, Release 6 of 3GPP TS 25.309, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; FDD Enhanced Uplink; Overall Description; Stage 2 (Release 6).
In HSUPA, certain attempts at enhancements are currently approached by distributing some of the packet scheduler functionality to the Node Bs to provide faster scheduling of bursty, non-real-time traffic than can be provided by the Layer 3 (L3, Network Layer) of the RNC. The idea is that with faster link adaptation it is possible to more efficiently share the uplink power resource between packet data users, as when packets have been transmitted from one user the scheduled resource can be made available immediately to another user. This technique attempts to avoid the peaked variability of noise rise, such as when high data rates are being allocated to users that are running bursty, high data-rate applications.
In the current architecture, the packet scheduler is located in the RNC and therefore is limited in the ability of the packet scheduler to adapt to the instantaneous traffic, because of bandwidth constraints on the RRC signaling interface between the RNC and the UE. Hence, to accommodate the variability, the packet scheduler must be conservative in allocating uplink power to take into account the influence from inactive users in the following scheduling period—a solution which turns out to be spectrally inefficient for high allocated data-rates and long release timer values.
Thus, with E-DCH much of the packet scheduler functionality is transferred to the Node B, i.e., there is a Node B scheduler that is responsible for allocating uplink resources. For the scheduling to be performed efficiently, the Node B needs to obtain some information from the UE. In 3GPP a so called ‘happy bit’ is defined, which is included in the E-DPCCH. The happy bit is always sent, and can indicate either “UP” (also called “unhappy”) or “KEEP” (also called “happy”). When the UE sends an “UP” request, the request means that the UE desires to obtain a higher bit rate (i.e., is “unhappy” with the current bit rate), while when the UE sends a “KEEP” request, this request means the UE is satisfied with (i.e., is “happy” with) the current bit rate.
3GPP defines that the UP-request (e.g., unhappy status) can be sent as follows:                The Happy Bit shall be set to “unhappy” if both of the following criteria are met:        UE has enough power available to transmit at higher E-DPDCH to DPCCH ratios than what is allowed by the current Serving_Grant; and        Total buffer status would require more thanHappy_Bit_Delay_Condition milliseconds (ms) to be transmitted with the current Serving_Grant.        
Reference in this regard can be had to Section 11.8.1.5 of 3GPP TS 25.321, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Medium Access Control (MAC) protocol specification (Release 6) (version 6.5.0) (2005-06).
A problem arises in defining the criteria of when the UE has power available to send at higher data rates (e.g., bit rates).
The E-TFCs are defined to have very small steps between them in order to have a relatively good fit to whatever size and number of higher layer data packets (SDUs) are to be transmitted. The small steps occur in transport block sizes of the transport blocks of the E-TFCs. However, the problem in the definition is that if the UE is currently transmitting with an E-TFC Y (e.g., transmitting a specific transport block size), then if the UE has enough power to transmit with E-TFC Y+1 (e.g., transmitting a slightly larger transport block size), the UE should not indicate “unhappy”. This is because the next E-TFC can, in a practical sense, almost never accommodate one more SDU, and thus cannot be used to transmit with a higher data rate. For instance, a slightly larger transport block size typically cannot accommodate another SDU.
Thus, the basic problem is that the data from higher layers come to the MAC in specific sized SDUs, and increasing the transmitted data rate means transmitting one or several additional SDU(s) in one transport block (e.g., in one E-TFC).